PubMed · 16280901
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2005. Too many problems.. https://doi.org/10.1097/00152193-200511000-00023
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Freshwater crayfish species in the subgenus Aviticambarus (Cambaridae: Cambarus) are restricted to caves along the Cumberland Plateau, the Sequatchie Valley, and the Highland Rim which extend along the Tennessee River in southcentral Tennessee and northern Alabama. Historically, three stygobitic species, Cambarus jonesi, Cambarus hamulatus, and Cambarus veitchorum, comprise this subgenus. We examine species' boundaries and phylogeographic structure of this imperiled Southern Appalachian assemblage to shed light on patterns of cave colonization. We also provide estimates of genetic diversity for conservation status assessment. Using geologic evidence, phylogeographic analyses, and sequence data from five gene regions (two nuclear: Histone H3 and GAPDH and three mitochondrial: 12S, 16S, and CO1 totaling almost 2700 base pairs), we identify two well-supported cryptic species in addition to the three currently recognized taxa. Four of these taxa exhibit low levels of genetic variation both currently and historically, which may indicate local extirpation events associated with geological and river basin changes. Our results also support other recent findings that pre-Pleistocene paleodrainages may best explain the current patterns of aquatic faunal biodiversity in the Southern Appalachians.
Anecdotal observations of the Dougherty plain cave crayfish (Cambarus cryptodytes), the Georgia blind cave salamander (Haideotriton wallacei), and albinistic isopods (Caecidotea sp.) at great depths below the land surface and distant from river corridors suggest that obligate aquifer-dwelling (troglobitic) organisms are widely distributed throughout the limestone Upper Floridan aquifer (UFA). One mechanism by which subterranean life can proliferate in an environment void of plant productivity is through a microbial food web that includes chemosynthesis. We examined this possibility in the UFA by measuring the isotopic composition ((13)C, (14)C, and (15)N) of tissues from troglobitic macrofauna. Organisms that were captured by cave divers entering into spring conduits had delta(13)C values that suggested plant matter as a primary food resource (cave crayfish, -24.6 +/- 2.7 per thousand, n = 9). In contrast, delta(13)C values were significantly depleted in organisms retrieved from wells drilled into areas of the UFA remote from spring and sinkhole conduits (cave crayfish -34.7 +/- 9.8 per thousand, n = 10). Depleted (13)C values in crayfish were correlated with radiocarbon (Delta(14)C) depletion relative to modern values. The results suggest that methane-based microbial chemosynthetic pathways support organisms living in the remote interior of the aquifer, at least in part.
OBJECTIVE: For unknown reasons, a previous preterm birth (PTB) is a major risk factor for PTB in the current pregnancy. Our goal is to evaluate placental histology for clues related to the recurrent nature of PTB. STUDY DESIGN: Four hundred fifty-seven mother/infant dyads delivering between 23 and 32 weeks were first classified as having a spontaneous (S) or indicated (I) PTB, and then sorted into the following mutually exclusive categories by pregnancy history: 1) nulliparous; 2) having no previous PTB; 3) having any previous IPTB; or 4) having a previous SPTB. The placentas were evaluated for acute inflammation in the free membranes, umbilical cord, and chorionic plate, chronic inflammation in the membranes and decidua basalis, thrombosis in the chorionic plate and umbilical cord, and diffuse decidual leukocytoclastic necrosis (DDLN), a lesion associated with decreased placental perfusion. RESULTS: Women who had a SPTB were far more likely (85.5 vs 14.4 P < .0001) to have a SPTB in the previous pregnancy, while women with an IPTB were significantly more likely to have had a previous IPTB (89.7 vs 10.3 P < .0001). Nulliparas and women with previous term births each had about 64% SPTB and 36% IPTB. Acute inflammation at any site was present in 73.9% of SPTB versus 8.0% of IPTB (P < .0001). Chorionic plate thrombosis was also more common in SPTB than IPTB (16.2 vs 7.6, P = .01). Chronic inflammation at any site was more common in IPTB than SPTB (21.0 vs 12.7%, P = .02), as was DDLN (46.5 vs 16.1, P < .0001). When classified by SPTB and IPTB in the current pregnancy, the histologic results were not further influenced by the previous pregnancy history. CONCLUSION: SPTB and IPTB are strongly repetitive. Women with SPTB are significantly more likely to have acute inflammation in the free membranes, chorionic plate, and cord, and chorionic plate thrombosis, while women with an IPTB are significantly more likely to have chronic inflammation and especially DDLN. Past obstetric history does not further influence the placental histology.